Pneumatic rubber tires are conventionally produced by molding and curing an uncured or green tire in a molding press, in which the green tire is pressed outwardly against a mold surface by means of an inner fluid expandable bladder. By this method, the green tire is shaped against the mold surface to define the tire's tread pattern and configuration of sidewalls. By application of heat, the tire is cured. Generally, the bladder is expanded by internal pressure provided by a fluid such as hot gas, hot water and/or steam which also participates in the transfer of heat for curing or vulcanization purposes. The tire is then usually allowed to cool in the mold, sometimes aided by added cold or cooler water to the internal surface of the bladder. The mold is then opened, the bladder collapsed by removal of its internal fluid pressure, and the tire removed from the tire mold. Such tire curing procedure is well known to those having skill in the art.
The use of synthetic rubber compounds in the manufacture of tires makes it necessary to apply suitable coatings to the rubber surfaces of the fabricated tire carcasses. The coatings ensure proper distribution of rubber during the curing operation and the production of finished tires with unblemished surfaces. The coatings are generally liquid in form, and are known as lubricants where applied to the interior surface of a green tire, and as anti-blemish paints where applied to the outer surface at the sidewall areas of the green tire.
The outside green tire paints allow the rubber to slip as it comes in contact with the metal mold, and the paints also serve as a release agent when the tire must separate from the mold at the end of the vulcanization cycle. Another function of the paint is to provide bleeding of air, which becomes trapped between the tire and the mold. Outside green tire paints also aid in the appearance of the finished tire.
Care must be taken that certain areas of the green tire are not coated, and that the lubricant employed at the interior of the carcass does not reach any exterior surface of the carcass. Also, applying the coatings manually by either spraying or brushing is time consuming and laborious. Automatic applications, are well known in the art, however, these prior art applications require presorting and separate applicators for tire size differences and outer spraying.
A known robotic tire spraying system is described in U.S. Pat. No. 7,943,201 to Hendricks, Sr., the entire disclosure of which is hereby incorporated herein by reference. The system analyzes individual green tires using an integrated vision system. The system controls the robotic spray position, the fan, fluid, atomizing air, and tire rotation speed for optimal spray coverage on both the inside and outside of green tires. The system includes a conveyor, an overhead mounted camera located over an infeed station, and a second camera located perpendicular to the green tire's tread and several feet away from the center of the tire. Pictures of the green tire in the station are used to estimate the center and radius of the tire and locate the angle of the bar code with respect to the center of the tire. Reference points are provided from the camera images and robot positions are calculated to control the spraying.
Another robotic tire spraying system is described in U.S. Patent Application Publication No. 2013/0078385. also to Hendricks, Sr. The system includes a downdraft spray booth for receiving a tire. A fluid delivery system is disposed in the spray booth, and includes at least one spray gun for delivering a coating to the tire. A robot transports the tire to the spray booth. Each of the spray booth, the fluid delivery system, and the robot are disposed on a platform, for convenient transport and installation of the system.
There is a continuing need for a precision fluid delivery system that minimizes overspray and provides uniform coverage of tires in tire spraying systems. Desirably, the precision fluid delivery system can be used to retrofit existing robotic tire spraying systems, and permits a fine adjustment of the tire spraying conditions in operation.